Offset epicyclic sickle drive for a header of an agricultural plant cutting machine

ABSTRACT

A compact epicyclic drive includes a pinion rotatable about a ring gear and an eccentric element fixedly connected to the pinion so as to be rotated thereby, a knife head bearing supported on and extending around the eccentric element, and a knife head assembly connected to a sickle knife assembly. The knife head assembly is configured so as to translate rotation of the eccentric element into sideward reciprocating movements of the sickle knife assembly, and to transfer forces resulting from the movements to a housing supporting the drive. Two of the drives can be utilized for reciprocatingly driving two of the sickle knife assemblies in opposite directions, such that the transferred forces will at least partially cancel one another.

TECHNICAL FIELD

This invention relates generally to a drive for the sickle of a headerof an agricultural cutting machine, such as a combine, windrower orother crop harvesting machine, or a mower, and more particularly, to adrive mechanism utilizing at least one epicyclic drive offset from asickle knife assembly driven thereby, and structure for containingmoments generated by the operation of the drive and reciprocatingmovements of the knife assembly.

BACKGROUND ART

Sickles typically including cutter bars supporting a row of knives, havebeen used to cut plants, including, but not limited to, hay, grasses,small grains and the like, for many years. The knives are composed of aplurality of knife or sickle sections which are mounted in side by siderelation forming an elongate metal knife assembly. The elongate knifeassembly is normally supported so as to slide longitudinally along anelongate stationary bar that has forwardly projecting, spaced apartguards bolted to a structural beam. The knife assembly moves back andforth in a reciprocating movement to move the knives relative to theguards so that the leading knife edges of the knives cross over theguards or through slots in the guards. This produces a shearing orcutting action which severs plant stems and stalks or other materialcaptured between the knives and the guards.

In a harvesting machine, such as a combine or windrower, the knifeassembly and stationary bar are typically supported in connection with acutting head or header, and are oriented so as to extend sidewardlyalong a forward edge portion of structure such as a floor or pan of theheader, hereinafter sometimes referred to generally as the floor. Thefloor or pan defines the lower periphery of a cut crop or plant flowarea, which can include conveying apparatus, such as one or more augersor belts, operable in cooperation with a reel in machines so equipped,for conveying the cut plant material and crops, for instance, to afeeder inlet of a combine or windrow forming apparatus of a windrower.

The knife assembly is driven reciprocatingly longitudinally by anoscillating drive, which can include, but is not limited to, aneccentric shaft on a rotating hub, a wobble drive, or a similar wellknown commercially available device. Such drives are typically locatedat the sides of the header, so as to drive the knife assembly from theend. This location is advantageous as it allows the driving point forthe knife assembly to be in line with the stationary bar, providesclearances for removal of the knife assembly, and provides space forassembly of the drive. Disadvantages of the side location include thatthe header must include significant frame structure for supporting thedrive and to withstand forces and vibrations generated thereby. The endstructure or crop divider at the end of the header must also berelatively wide, to accommodate the drive and to direct adjacentstanding crops therepast, and increasing the possibility of accidentallypushing down adjacent standing crops. Additionally, for headersutilizing two drives located on opposite sides of the header, it isusually desired to time the operation of the drives such that the forcesand vibrations generated by the respective drives cancel one another.This typically involves relatively long mechanical drive linesconnecting the two drives together, which is disadvantageous as it addsweight, cost and complexity.

A knife assembly, which will weigh from 35 to 38 pounds for a typical 20foot wide header, typically must accelerate and decelerate two times percycle as a result of the reciprocating movement. A typical speed for theknife assembly is up to about 16 hertz or cycles per second. Thus, itcan be seen, the reciprocating motion at a high cycle per secondgenerates high acceleration values and high deceleration values that inturn generate high forces on the structural components. These highforces can have at least two negative effects, vibration at the drivesystem that may be transmitted to other components of the machine, andfatigue failure of the structural components themselves. On largerheaders, for instance, headers 30feet wide and greater, two knifeassemblies each equal to one-half the sideward extent of the header areoften used.

Driving a knife assembly or assemblies of a header from a more centrallocation, such as the center of the header, would provide severaladvantages compared to a side location. Notably among these advantages,the header structure would not be required to support heavy drive unitson one or both sides, such that the structure of the header could belighter. Long timing apparatus extending between the ends could also beeliminated. If the drive mechanism could be incorporated into a locationthat would not interrupt or require dividing crop or plant material flowthrough the crop flow area of the header, the normal crop flow of theheader would not be significantly impacted. And, since the drives arenot located in the ends, the end dividers can be made significantlythinner, such that the header can have a shorter overall width, would bemore easily maneuverable in relation to adjacent standing crop, anddanger of downing the adjacent standing crop would be reduced.

Thus, what is sought is a drive for a sickle of a header of anagricultural cutting machine, such as a combine or windrower, whichovercomes one or more of the problems, negative effects, anddisadvantages referenced above.

SUMMARY OF THE INVENTION

What is disclosed is a compact drive mechanism for a sickle of anagricultural cutting machine, such as a combine, windrower, or othercrop harvesting machine, which overcomes one or more of the problems,negative effects, and disadvantages set forth above.

According to a preferred aspect of the invention, the compact drivemechanism is adapted to be located beneath, or incorporated into, afloor or pan of a header at a location spaced from the sides or ends ofthe header, such that cut crops or other plant material can flow overand around the drive mechanism and not be obstructed thereby. The drivemechanism of the invention is preferably configured for driving twoknife assemblies of a sickle disposed in end to end relation,reciprocatingly in opposite directions, such that forces generated bythe moving masses of the drive mechanism and the two knife assemblies,including forces resulting from moments, are at least substantiallycompletely contained within the structure of the drive mechanism, andtherefore are not directed to structure of the header. As a result,large, heavy drive units and support structure adequate for withstandingvibrations and high back and forth forces, are eliminated from the sidesor ends of the header, as is timing apparatus for connecting the drives,and the crop dividers on the sides can be narrower.

According to another preferred aspect of the invention, the compactsickle drive mechanism includes two epicyclic drives, one for each oftwo knife assemblies of a sickle. The epicyclic drive for driving eachknife assembly includes an input element supported beneath the floor orpan for rotation about a central rotational axis through the inputelement, and a pinion gear supported in connection with the inputelement for rotation relative thereto about an eccentric axis offsetfrom and parallel to the central rotational axis. The epicyclic driveincludes a fixed ring gear, mounted on a frame or mounting structure ofthe drive, which ring gear is concentric with the input element andenmeshed with the pinion gear such that rotation of the input elementabout the central rotational axis will cause the pinion gear to rotatearound the ring gear about the central rotational axis andsimultaneously rotate about the eccentric axis, in essentially anorbiting movement. The epicyclic drive includes an eccentric elementfixedly connected to the pinion gear so as to be rotated therebyeccentrically about the ring gear and the central rotational axis whenthe input element is rotated. And the drive includes a knife head driverelement connected to the knife assembly and supported for sidewardmovement therewith along the forward edge portion of the floor. Theknife head driver element is rotatably connected to the eccentricelement by a knife head assembly. The knife head assembly includes anelement which extends around the eccentric element and is configured soas to transfer sidewardly directed components of the eccentric rotationsof the eccentric element into sideward reciprocating movements of theknife assembly, and rollers or another guide or guide member configuredfor containing or guiding movements of the element. The rollers or otherguides are mounted on the housing or frame of the drive mechanism, andprovide a means for transfer of forces generated during thereciprocating movements of the sickle knives, to the housing or frame.The eccentric element and knife head assembly are verticallycoextensive, so as to contribute to the overall compactness of the drivemechanism. And, the eccentric element has a sufficient diametricalextent so as to accommodate the sideward extent of movement of the knifeassemblies.

Preferably, the two epicyclic drives are mounted in side by siderelation, and are connected in reciprocatingly driving relation to twoknife assemblies, respectively, preferably supported in end to endrelation adjacent to the front edge portion of the floor or pan of aheader, for simultaneously moving the knife assemblies reciprocatinglyin opposite sideward directions. The timing also causes the eccentricelements of the respective drives to eccentrically rotate in timedrelation, such that radial forces generated by imbalances of therespective eccentric elements are also at least substantially cancelled,resulting in the net overall forces and vibrations emanating from thetwo drives and knife assemblies being greatly reduced or evensubstantially eliminated.

According to another preferred aspect of the invention, the drivemechanism is configured such that the two epicyclic drives are jointlydriven by a common drive, preferably in timed relation one to the otherusing a timing belt drive, chain drive and/or gear drive. The commondrive can be a motor, such as a fluid or electric motor, a PTO shaft, orthe like.

Still further, as another preferred aspect of the invention, the compactdrive mechanism is configured such that the two epicyclic drives arecommonly supported on a support frame or structure, and are commonlyhoused. As another preferred aspect, the epicyclic drives of theinvention can also be supported in connection with the knife assemblies,for instance, mounted in connection with the rear ends thereof, so as tobe movable upwardly and downwardly therewith relative to the floor orpan of the header, in a floating operating mode, to move forwardly andrearwardly therewith if used on a variable floor type header, and toallow some angular movement of the knife assemblies if used on a flexheader.

As examples of preferred embodiments according to the invention, for awide range of typical agricultural combine grain header having a widthof from about 20 to about 40 feet, a compact drive mechanism located atabout the center of the header, spaced equally from the opposite ends,and including two epicyclic drives, can be used. Each epicyclic drivewould be connected to a knife assembly having a length equal to aboutone half the width of the header. Or, for a wider combine grain headerwithin this range, for instance, having a width of from about 36 toabout 40 feet, it is contemplated that two compact drive mechanisms eachincluding two epicyclic drives could be used, each epicyclic drive beingconnected to a knife assembly having a length equal to about one fourththe width of the header. This latter arrangement would also haveparticular utility for draper headers, that is, headers having elongatemoving belts which convey plant material sidewardly toward a centralbelt which conveys the plant material rearwardly into a feeder of acombine, or into windrowing apparatus of a windrower. As still anotherexample, when a drive mechanism of the invention is used with a shorterand/or lighter weight sickle, the drive can be operated at a higherreciprocating speed, to allow operation of the harvesting machine at ahigher ground speed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a forward end view of a combine including a header having acompact sickle drive mechanism according to the present invention;

FIG. 1 a is an enlarged fragmentary forward end view of an end of theheader of FIG. 1;

FIG. 1 b is an enlarged fragmentary forward end view of the end of theheader of FIG. 1 including a prior art sickle drive;

FIG. 2 is an enlarged fragmentary top view of the header of FIG. 1, witha cover and an upper bearing assembly removed to show other aspects ofthe drive mechanism of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view of the header takengenerally along line 3-3 of FIG. 2, and with the cover and a floor ofthe header in phantom to reveal the drive mechanism;

FIG. 3 a is another enlarged fragmentary sectional view of the headertaken generally along line 3-3 of FIG. 2, with the sickle and drivemechanism moved vertically relative to the floor of the header toillustrate utility of the invention for headers having a floatingcapability;

FIG. 4 is a top view of the drive mechanism of FIG. 1, showing the upperbearing assemblies in place;

FIG. 4 a is a top fragmentary view of the header and drive mechanism ofFIG. 1, illustrating connection of the drive mechanism with analternative power source which is a PTO shaft;

FIG. 4 b is another top fragmentary view of the header and drivemechanism of FIG. 1, illustrating connection of the drive mechanism withanother alternative power source which is an electric motor;

FIG. 5 is a fragmentary sectional view of a portion of the drivemechanism taken along line 5-5 of FIG. 4, illustrating internal aspectsthereof;

FIG. 5 a is an enlarged fragmentary sectional view of a portion of thedrive mechanism of FIG. 5, illustrating a dust cover thereof;

FIG. 5 b is an exploded view of an upper portion of the drive mechanism;

FIG. 5 c is a perspective view of a housing of the drive mechanism;

FIG. 6 is a top view of the drive mechanism of FIG. 1, illustratingelements thereof in a first representative operating position;

FIG. 6 a is a simplified schematic top view of the drive mechanism ofFIG. 1 in the operating position of FIG. 6;

FIG. 6 b is a simplified schematic top view of a pinion gear and ringgear and an eccentric element of the drive mechanism of FIG. 1 for theoperating position of FIG. 6;

FIG. 6 c is a fragmentary top view of the drive mechanism of FIG. 6,illustrating a timing drive belt;

FIG. 7 is another top view of the drive mechanism of FIG. 1,illustrating elements thereof in a second representative operatingposition;

FIG. 7 a is a simplified schematic top view of the drive mechanism ofFIG. 7;

FIG. 7 b is a simplified schematic top view of the pinion gear and ringgear and eccentric element of the drive mechanism of FIG. 7;

FIG. 8 is a simplified schematic top view of the drive mechanism of FIG.1, illustrating elements thereof in a third representative operatingposition;

FIG. 8 a is a simplified schematic top view of the pinion gear, ringgear and eccentric element of the drive mechanism of FIG. 8;

FIG. 9 is another top view of the drive mechanism of FIG. 1,illustrating elements thereof in another representative operatingposition;

FIG. 9 a is a simplified schematic top view of the pinion gear, ringgear and eccentric element of the drive mechanism of FIG. 9;

FIG. 9 b is a simplified schematic top view of the pinion gear, ringgear and eccentric element of the drive mechanism of FIG. 9;

FIG. 10 is a forward end view of the combine of FIG. 1 including aheader having a compact sickle drive mechanism according to the presentinvention;

FIG. 11 is a forward end view of the combine of FIG. 1 including aheader utilizing two compact sickle drive mechanisms of the invention;

FIG. 12 is a fragmentary top view of the combine of FIG. 11, with aportion of a draper belt thereof removed to reveal a sickle drivemechanism of the invention; and

FIG. 13 is a forward end view of a conventional windrower including aheader having a compact sickle drive mechanism according to the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

Turning now to the drawings wherein several preferred embodiments of theinvention are shown, in FIG. 1, a conventional, well known agriculturalcutting machine, which is a combine 20, is shown including a header 22.Header 22 is shown supported in the conventional, well-known manner on aforward end 24 of combine 20, and is operable for cutting or severingcrops such as, but not limited to, small grains such as wheat andsoybeans, and inducting the severed crops into a feeder 26 forconveyance into combine 20 for threshing and cleaning, in the well knownmanner, as combine 20 moves forwardly over a field.

Referring also to FIGS. 2 and 3, header 22 includes a pan or floor 28which is supported in desired proximity to the surface of the fieldduring the harvesting operation, and an elongate, sidewardly extendingsickle 30 along a forward edge portion 32 of floor 28, sickle 30 beingoperable for severing the crop for induction into header 22, as will beexplained. Header 22 additionally includes an elongate, sidewardlyextending reel 34 (FIG. 1) disposed above sickle 30 and rotatable in adirection for facilitating induction of the severed crops into header22. An elongate, rotatable auger 36 (shown in outline form in FIG. 1)that extends in close proximity to a top surface 38 of floor 28 and hashelical flights therearound (not illustrated) is operable in cooperationwith reel 34 for conveying the severed crops toward an inlet opening offeeder 26 for induction into combine 20, in the well-known manner.

Referring more particularly to FIG. 1, sickle 30 extends in a sidewarddirection along the width of floor 28, between a first side edge portion40 of the floor, and an opposite second side edge portion 42. Sickle 30includes an elongate, sidewardly extending first cutter bar assembly 44,and an elongate, sidewardly extending second cutter bar assembly 46extending in end to end relation to cutter bar assembly 44, cutter barassemblies 44 and 46 being supported in substantially longitudinallyaligned relation adjacent to forward edge portion 32 of floor 28.

Referring more particularly to FIGS. 2 and 3, cutter bar assemblies 44and 46 each include a plurality of sidewardly facing aligned slots 48through a sidewardly extending array of guards 50 which projectforwardly from a stationary bar 52 at sidewardly spaced intervalstherealong. Stationary bar 52 extends the length of sickle 30 justforwardly of forward edge portion 32 of floor 28, and guards 50 aremounted to bar 52 with fasteners 54. Bar 52, in turn, is mounted to aframe 58 at the bottom of header 22, as also illustrated in FIG. 3. Eachof cutter bar assemblies 44 and 46 supports an elongate knife assembly60 for reciprocating longitudinal movement within slots 48, each knifeassembly 60 including a row of knife sections including oppositelyfacing, angularly related knife edges 62 which, in conjunction withadjacent guards 50, effects a shearing or cutting action which seversplant stems and stalks or other material captured between the knives andthe guards as the knife sections are reciprocatingly moved sidewardly,as denoted by arrows A.

As noted above under the Background Art heading, it is desirable toreduce negative effects of the reciprocating sideward motion of knifeassemblies 60, including, but not limited to, vibration, fatiguefailure, and the like, and also the disadvantages of known structuresfor effecting the motion, including the need for substantial structurefor supporting drive mechanisms on the sides of headers, the increasedwidth of side dividers containing the mechanism, and apparatus fortiming drive mechanisms located on opposite sides of a header.

Reduction of these negative effects and disadvantages is achievedaccording to the present invention by utilizing a compact sickle drivemechanism 66 constructed and operable according to the teachings of thepresent invention. Sickle drive mechanism 66 is illustrated in FIG. 1 ata location on header 22 between side edge portions 40 and 42 which is atabout the center of header 22, although it should be noted that it iscontemplated that sickle drive mechanism 66 could alternatively beutilized at other locations on a header such as header 22, and thatmultiple sickle drives 66 could be used on a header, as described andillustrated later herein.

Referring also to FIGS. 3, 3 a and 4, compact sickle drive mechanism 66includes a first knife head driver element 68 in connection with theknife assembly 60 of first cutter bar assembly 44, and a second knifehead driver element 70 in connection with the knife assembly 60 ofsecond cutter bar assembly 46, knife head driver elements 68 and 70being simultaneously operable by drive mechanism 66 for reciprocatinglydriving the knife assemblies 60 of respective cutter bar assemblies 44and 46 sidewardly, as illustrated by arrows A, in timed relation so asto move in opposite sideward directions. That is, as knife assembly 60of first cutter bar assembly 44 is moved in one sideward direction,knife assembly 60 of second cutter bar assembly 46 will be moved in theopposite sideward direction. The length of the sideward movements, orstrokes, will be sufficient for providing the desired cutting action,which will typically be equal to about the sideward extent of a knifeedge 62 of a typical knife section, as generally denoted by distance Bin FIG. 4. First and second knife head driver elements 68 and 70 arepreferably constructed of a sheet or cast metal bent or formed to asectional shape about as shown, and are connected to knife assemblies 60of the respective cutter bar assemblies 44 and 46 in a suitable manner,here using sidewardly extending elongate bars 72 on the forward ends ofdriver elements 68 and 70, which connect to the knife assemblies 60 withsuitable fasteners such as screws 74 or the like. Here, it should benoted that it is desired for the knife assemblies 60 to move only in thesideward directions relative to stationary bar 52, and not forwardly,rearwardly, upwardly or downwardly to any significant extent relativethereto. This is achieved at least in large part by the containment ofknife assemblies 60 in slots 48 of stationary bar 52, although otherconstructions for holding the knife assemblies could be used. Becausedriver elements 68 and 70 are rigidly connected with knife assemblies60, respectively, driver elements 68 and 70 are also restricted tosideward movements only.

Compact drive mechanism 66 includes a first epicyclic drive 76 connectedin driving relation to first knife head driver element 68, and a secondepicyclic drive 78 connected in driving relation to second knife headdriver element 70, epicyclic drives 76 and 78 being contained in acompact common housing 80 of drive mechanism 66 mounted, for instance,on frame 58 of header 22. Housing 80 is best illustrated in FIG. 5 c. Itis contemplated and preferred that compact sickle drive mechanism 66 beincorporated in or beneath floor 28 of header 22, sufficiently such thatcut plant material, particularly crops, cut by those portions of cutterbar assemblies 44 and 46 forwardly of drive mechanism 66 will be able torelatively smoothly and uninterruptedly flow over and around drivemechanism 66 so as to enter a plant or crop flow area 82 above floor 28,and so as to subsequently be conveyed, for instance, by reel 34 andauger 36, to the inlet of feeder 26 of combine 20. To facilitate this,drive mechanism 66 is vertically compact, preferably having a verticalextent of no more than about six inches, and is preferably disposedbeneath and covered by a smooth, low profile, streamlined upper cover 84which preferably is of sheet metal or similar construction and forms apart of floor 28 and top surface 38 thereof at the center of header 22.Cover 84 preferably has a forwardly facing slot or slots through whichdriver elements 68 and 70 extend, but which slots are sufficientlynarrow so as to at least substantially prevent passage of cut plantmaterial through the slot or slots and into the interior of cover 84.Here, it should be noted that epicyclic drives 76 and 78 each preferablyincludes an upper bearing assembly 86 (deleted in FIG. 2 to reveal otheraspects of the drives), which is illustrated in FIGS. 3, 3 a and 4 asbeing external to housing 80, but which, alternatively, could beincorporated within the housing 80. The bottom region of housing 80 isalso preferably enclosed, to prevent entry of contaminants into theinterior thereof.

In FIG. 3 a, frame 58, sickle 30, compact drive mechanism 66 and cover84 are shown in a lowered position relative to floor 28, forfacilitating a floating sickle capability, and illustrates theadaptability of drive mechanism 66 for use with a header such as header22 having this capability. Here, it is contemplated that this featurewould have utility for use when harvesting grains, such as soybeans,wherein a floating capability is typically used. Alternatively, frame58, sickle 30 and drive mechanism 66 can be fixed and locked in a raisedposition, as illustrated in FIG. 3, as would typically be used forharvesting wheat. Additionally, the apparatus of the invention can beconfigured for use with flexible sickles or cutter bars assemblies, forinstance, by allowing some sideward twisting or rotation of thestructure such as frame 58 supporting mechanism 66. And, the apparatusof the invention can be configured for use with variable floor headerswherein the cutter bar assembly and possibly a leading edge of the flooris fore and aft movable relative to the more rearward region of thefloor.

Knife assemblies 60 are preferably reciprocatingly driven in timedrelation by the respective epicyclic drives 76 and 78 so as to move inopposite sideward directions, such that forces generated by the movingmasses of the knife assemblies are at least substantially containedwithin the structure of the invention, thereby substantially reducing oreliminating transfer of vibrations to the structure of header 22, and,from there to combine 20. Preferably, a common power source is used,which can be, but is not limited to, a fluid motor 88. Fluid motor 88 isillustrated as being mounted to a rear end 90 of housing 80. Fluid motor88 is connected in rotatably driving relation to a horizontal rotatableinput shaft 92 supported by a bearing 94 mounted within housing 80, andin connection with a bevel gear 96 enmeshed at a right angle with asecond bevel gear 98. Second bevel gear 98, in turn, is mounted inconnection with a vertical input shaft 100 mounted within housing 80.Fluid motor 88 is connected to a source of pressurized fluid and a fluidreservoir (not shown) on combine 20 in the conventional, well-knownmanner, via fluid lines 102 and 104 (FIG. 2) and is operable forrotating input shaft 92, which in turn rotates bevel gears 96 and 98 torotate shaft 100. This provides the power to first and second epicyclicdrives 76 and 78, which are configured to translate the power into thesideward reciprocating movements of first and second knife head driverelements 68 and 70, and thus of knife assemblies 60, as will beexplained.

Referring also to FIGS. 4 a and 4 b, as noted above, drive mechanism 66can be driven by an alternative power source, which can include, but isnot limited to, a PTO shaft 106 (FIG. 4 a), or an electric motor 108(FIG. 4 b), or other common driver such as a belt or chain (not shown)or a combination of such drives. In either of the illustrated instances,the alternative power source 106 or 108 can be connected in rotatablydriving relation to drive mechanism 66 via an input shaft 92 or othersuitable manner of connection. Here, it should be noted that the rightangle drive capability provided by bevel gears 96 and 98 facilitatesvertical compaction of drive mechanism 66. And, as an alternative, itshould be noted that first and second epicyclic drives 76 and 78 couldbe driven separately.

Referring also to FIG. 5, a cross-sectional view of second epicyclicdrive 78 illustrates the features thereof that enabled the verticalcompactness of drive mechanism 66. Referring also to FIG. 6, another topview of sickle drive mechanism 66 is shown, illustrating aspects ofmechanism 66 for operating drives 76 and 78 in timed relation. Moreparticularly in this latter regard, input shaft 100 includes a cog beltsheave 110 partially encircled by a cogged timing drive belt 112. A pairof idler wheels 114 increase the wrap of belt 112 about sheave 110.Timing drive belt 112 is routed about the inner periphery of housing 80to partially encircle an input element 116 of each of epicyclic drives76 and 78. Here it should be noted that first and second epicyclicdrives 76 and 78 share a common construction, but are timed differentlysuch that, although rotated in the same direction by drive belt 112,first and second driver elements 68 and 70 will be simultaneously drivenin opposite sideward directions, as will be explained. Input elements116 of the respective drives 76 and 78 each comprise a flywheel having acogged outer circumferential surface 118 engaged with cogged timing belt112, as illustrated in FIG. 6 c. Alternatively, a chain or gear drive,or a combination drive, could be used to accomplish a timed drivecapability.

Input element 116 of each drive 76 and 78 is mounted for rotation abouta central rotational axis 120 of the drive, on a fixed frame 122 of castmetal or other sturdy construction which is part of housing 80. This isachieved using a downwardly extending annular bearing flange 124 onframe 122, which defines a downwardly facing round cavity, and includesan inner circumferential bearing seat 126 into which a bearing 128 issuitably mounted and retained, for instance, using a snap ring 132.Central rotational axis 120 of each drive extends in and defines anaxial direction for the drive. Input element 116 includes an inner hub130 sized to be received in the downwardly open cavity and having anouter circumferential surface around which bearing 128 is retained, forinstance, by a press fit, snap ring, or other suitable manner ofmounting. Installation of ring 132 can be accomplished, for instance,using one or more holes that can be provided through input element 116,or in any other suitable manner. Hub 130 includes a hole 134 therein ata location offset from central rotational axis 120, and through which aneccentric axis 136, parallel to, but offset from rotational axis 120,extends. A bearing seat 138 extends around a portion of hole 134 andreceives a bearing 140 which is suitably retained in position by aretainer ring 142, a press fit, or like.

The lower end of a pinion shaft 146 is received in pinion bearing 140and secured thereto by a bolt 144 and a washer for rotation relative toinput element 116, and extends upwardly through a central passage 148extending through frame 122 and concentric about central rotational axis120.

A ring gear 150 is fixedly mounted on or incorporated into frame 122 soas to extend around central passage 148. Pinion shaft 146 includes apinion gear 152 enmeshed with ring gear 150, such that when inputelement 116 is rotated about central rotational axis 120, pinion gear152 will cause pinion shaft 146 to rotate therewith about eccentric axis136, while circling or orbiting about central rotational axis 120. Here,the internal pitch diameter of ring gear 150 is preferably selected tobe equal to twice the pitch diameter of pinion gear 152, such that foreach revolution of input element 116, pinion shaft 146 and pinion gear152 about central rotational axis 120, pinion shaft 146 and gear 152will be rotated two revolutions about eccentric axis 136.

Referring also to FIG. 5 b, pinion shaft 146 extends upwardly aboveframe 122 so as to be located above housing 80, and an eccentric element154 is mounted to the upwardly extending pinion shaft 146, also abovehousing 80. These elements can be viewed from above when upper bearingassembly 86 is removed, as shown in FIGS. 2 and 6. Eccentric element 154is a round or disc shaped member and is mounted to pinion shaft 146 soas to be eccentric to eccentric axis 136 therethrough. Pinion shaft 146also preferably extends above eccentric element 154 so as to be receivedin a hole 156 in an upper bearing plate 158 of upper bearing assembly86. A bolt 160 threadedly engaged with the upper end of pinion shaft 146retains upper bearing plate 158 and eccentric element 154 on shaft 146.A splined, a tri-lobe type, or other suitable connection would be usedto position and maintain position of elements 154 and 158 relative toeach other and to the pinion. A spacer 162 is disposed around pinionshaft 146 between eccentric element 154 and upper bearing plate 158.Additionally, also referring to FIG. 5 a, a seal 164 and a shoulder or aspacer 166 extend around pinion shaft 146 in a space between eccentricelement 154 and an upper surface of frame 122 of housing 80. Seal 164 ispreferably a lip type seal and covers central passage 148, to limit orprevent entry of water, dust and other contaminants into central passage148.

Referring more particularly to FIGS. 4, 5, and 5 b, circular or discshaped upper bearing plate 158 is retained by a bearing 168 supported ina fixed bearing frame 170 of upper bearing assembly 86 attached tohousing 80, such that bearing plate 158 is rotatable about centralrotational axis 120 concentric with input element 116. Fixed bearingframe 170 illustrated is a split or saddle type bearing frame having asemicircular bearing cap 172 held in place on frame 170 by bolts or capscrews 174, for holding bearing 168 in axial alignment with centralrotational axis 120, although other suitable bearing structures can alsobe used. Here, it should be noted that in the sectional view of FIG. 5pinion shaft 146, pinion gear 152, upper bearing plate 158 and bolt 160are illustrated in a rotational position about central rotational axis120 (as illustrated by bolt 160 in dotted lines in FIG. 4) which isrotated 90° counterclockwise from that represented by bolt 160 in solidlines in FIG. 4, so as to better illustrate the offset, eccentricrelationship of those elements with respect to central rotational axis120.

Referring more particularly also to FIG. 6, eccentric element 154 ofeach epicyclic drive 76 and 78 is circular or disc shaped and supports aknife head assembly 176 on a bearing 178, such that eccentric element154 and assembly 176 are relatively rotatable in a plane perpendicularto axes 120 and 136. Assembly 176 of each drive 76 and 78 is offsetrearwardly from the knife head 60. Assembly 176 includes an elementsupported on and extending about bearing 178 and rigidly connected torespective knife head driver element 68 or 70 which extends forwardlytherefrom to connect with the respective knife head 60, and includes anarm portion 180 extending sidewardly therefrom and between a pair ofrollers 182 mounted externally on the top surface of housing 80. Itshould be observed that assemblies 176 are inverted mirror images of oneanother, such that arm portion 180 extend from opposite directionstoward the center of drive mechanism 66. This is important, as will beexplained. Rollers 182, in cooperation with the containment of knifeassemblies 60 in the slots of guards 50, restrain assembly 176, driverelements 68 and 70, and knife assemblies 60 from forward and rearwardmovement, but allow sideward movement thereof toward both ends or sidesof the header, even through the full range of rotation of eccentricelements 154. Since, as a result of the rearward offset, knifeassemblies 60 are located some distance forward of sickle drive 66, andparticularly of housing 80 and rotational axes 120, and are driven withconsiderable forces which can reach thousands of pounds, the forces fromthe acceleration and deceleration of knife assemblies 60 generatesubstantial force moments around axes 120. Such moments are restrainedby arm portions 180 of knife head assemblies 176 through rollers 182mounted to housing 80, keeping the forces contained within housing 80.Here, it should be noted that to achieve vertical compactness,concentric element 154, knife head assembly 176, and bearing 178, are atleast generally vertically coextensive. Additionally, those elementspreferably have a vertical extent of about 2 inches or less, and morepreferably, of about 1 inch or less.

In FIG. 6, it should also be noted that knife assemblies 60 areillustrated in a mid-stroke position wherein guards 50 are disposedabout equidistant between knife edges 62 of adjacent knife sections. Inthis position, eccentric elements 154 of both drives 76 and 78 are aboutconcentric with the central rotational axis 120 of the respective drive.However, pinion shaft 146 of drive 76 is illustrated disposed above(actually rearwardly of) central rotational axis 120 of that drive,whereas pinion shaft 146 of drive 78 is illustrated disposed below(forwardly of) central rotational axis 120 of that drive. This isimportant, as the position of pinion shaft 146 about central rotationalaxis 120 of each drive 76 or 78 will establish the direction of sidewardmovement and position of the respective knife assembly 60 connected tothat drive. For the examples, belt 112 will be assumed to move in theclockwise direction denoted by arrow C at the top of the drawing. Here,it can be observed that eccentric element 154 will have a diametricalextent within the bounds of bearing 178 which at least equals thesideward extent of movement of the knife head, to accommodate therotational movement of pinion shaft 146 which produces the sidewardmovement.

Referring also to FIG. 6 a, knife head assemblies 176 of drives 76 and78 are again illustrated in the mid-stroke position. Pinion shaft 146 ofdrive 76 is disposed directly above (rearwardly of) central rotationalaxis 120 of that drive. Pinion shaft 146 of drive 78 is disposeddirectly below (forwardly of) central rotational axis 120 of that drive.Arm portions 180 of both drives are about midway along their extents oftravel in contact with their respective rollers 182. FIG. 6 b is aschematic representation of the position of pinion shaft 146 of drive 78when in the position shown in FIGS. 6 and 6 a. Pinion gear 152 is shownengaged with ring gear 150, which it should be remembered, is concentricwith central rotational axis 120. Eccentric element 154 of that drive isalso concentric with axis 120. In this position, as pinion shaft 146 iscaused to orbit or circle in the clockwise direction about centralrotational axis 120, as denoted by arrow D, resulting from the rotationof input element 116 by belt 112 (FIG. 6) as explained earlier, pinionshaft 146 will be caused to rotate in the counterclockwise directionabout eccentric axis 136 therethrough, as denoted by arrow E, as aresult of the engagement of pinion gear 152 with ring gear 150. Thiswill result in eccentric element 154 also being rotated counterclockwisein direction E, to the position shown in FIG. 7 b. This also illustratedin FIGS. 7 and 7 a. As a result of the restraint of knife headassemblies 176 so as to be movable sidewardly only, and the presence ofbearings 178, eccentric elements 154 are allowed to rotate relative tothe respective assembly 176, with the further result that assemblies 176are displaced sidewardly. Here, knife head assembly 176 of drive 76 isdisplaced or stroked sidewardly inwardly toward the right as denoted byarrow F in FIG. 7, while knife head assembly 176 of drive 78 isdisplaced or stroked sidewardly inwardly toward the left, as denoted byarrow G. This position illustrated in FIG. 7 represents the maximuminward extent of the cutting strokes of knife assemblies 60. Referringto FIGS. 6 a and 7, movement in directions F and G (FIG. 7) results ingeneration of moments against rollers 182, as a result of knifeassemblies 60 being located forward of sickle drive 66 and theconsiderable forces required for acceleration and deceleration of thelong knife assemblies, and opposition generated by the cutting actionand friction, which moment forces can reach thousands of pounds and willbe contained within the structure of the drive. More particularly, armportions 180 of knife head assemblies 176 are oriented so as to extendin opposite sideward directions corresponding to the directions ofmovement of knife assemblies 60. When such moment forces are present,arm portions 180 will bear against rollers 182, which are secured onhousing 80, such that the moment forces are transferred through armportions 182 housing 80. And, because the moment forces of the twodrives are exerted simultaneously in opposite directions, they willessentially act against one another, to minimize forces exerted by drivemechanism 66 against the structure of the header. Referring briefly toFIG. 5 c, the upper surface of housing 80 includes robust mountingelements 218 which received and support rollers 182 rotation by armportions 182. This rotatability of rollers 182 is advantageous also asit reduces friction.

Referring also to FIGS. 8 and 8 a, knife head assemblies 176 of drives76 and 78 are again illustrated in the mid-stroke position, aftercontinued movement of pinion shafts 146 in direction D about axis 120,as effected by continued rotation of input elements 116 in direction C(FIG. 6). This, in turn, effects a corresponding reversal of thesideward directions of movement of knife head driver elements 68 and 70to a sideward outward direction (arrows H and J), from those shown inFIG. 7 (arrows F and G). Arm portions 180 of both drives are aboutmidway along their extents of travel in contact with their respectiverollers 182, such that the knife assemblies will be positioned asillustrated in FIG. 6. In FIG. 8 b, pinion gear 152 of drive 78 hascontinued rotation in direction E about axis 136 around ring gear 150and axis 120, and eccentric element 154 of that drive is also againconcentric with axis 120. Again, eccentric elements 154 are allowed torotate relative to the respective knife head assembly 176, with theresult that assemblies 176 are displaced sidewardly only. During thisdirection of movement, moment forces are generated in the oppositedirections against rollers 182 compared to those shown in FIG. 6 a, asdenoted in FIG. 8, which moments will be contained within the structureof the drive.

Turning to FIGS. 9, 9 a and 9 b, knife head assemblies 176 of drives 76and 78 are now illustrated moved further in the sideward outwarddirections H and J to their sideward outermost positions, as a result offurther continued movement of pinion shafts 146 in direction D aboutaxis 120, as effected by continued rotation of input elements 116 indirection C. Arm portions 180 of both drives are at their farthestoutward extents of travel in contact with their respective rollers 182.Knife assemblies 60 are illustrated in about an outward end of theirstrokes after passage of the knife edges 62 through guards 50 in anoutward cutting stroke. In FIG. 9 b, pinion gear 152 of drive 78 hascontinued rotation in direction E about axis 136 around ring gear 150and axis 120, and eccentric element 154 of that drive is shiftedsidewardly outwardly of axis 120. Again, eccentric elements 154 areallowed to rotate relative to the respective assembly 176, with theresult that assemblies 176 are displaced sidewardly only. With continuedmovement of pinion shafts 146 in direction D about axis 120, as effectedby continued rotation of input elements 116 in direction C, the elementsof drives 76 and 78 will return to the positions illustrated in FIG. 6,and thus completing a complete revolution of pinion shafts 146 aboutcentral rotational axes 120, which corresponds to a complete revolutionof input elements 116 of the drives.

Here, as an advantage of the invention, it should be apparent that knifehead assemblies 176 and driver elements 68 and 70 are moved by drives 76and 78 in opposite sideward directions, such that sideward forcesexerted respectively thereby are at least substantially canceled.Additionally, forces generated by eccentric movements of respectiveeccentric plates 158 will at least substantially cancel one another, asthe eccentric movements are in opposite directions. Additionally, thestructure of the drives is strong and robust, so as to be capable ofcontaining forces resulting from the moments generated by theaccelerations and decelerations of the knife assemblies, which can besubstantial. As a result, vibrations and forces exerted by drivemechanism 66 against supporting framework, such as frame 58 of header22, will be minimal.

Referring also to FIGS. 1 a and 1 b, as another advantage, because thecompact sickle drive mechanism of the invention can be mounted betweenthe side or end portions of a header as illustrated herein, the space onthe side of the header where the sickle drive would otherwise be locatedcan be eliminated, such that the width of the crop divider on that sidecan be significantly reduced. This is illustrated in FIG. 1 a, wherein aconventional crop divider 184 is used that contains no sickle drive.Crop divider 184 will have an overall width 186 of about 4 inches. Incontrast, a conventional prior art crop divider 188 is illustrated,which is sufficiently wide to accommodate a conventionally constructedand located wobble drive 190, a drive belt sheave 192 for powering drive190, and a cover 194. A typical overall width for an arrangement such asthis, denoted by width 196, will be from about 8 to about 10 inches. Asa result, when a header, such as header 22, utilizing a drive mechanismof the invention is driven through a field of standing crop forharvesting a swath of the crop, the narrower width of crop divider 184compared to divider 188 will reduce the amount of crop that may bepushed down by the divider and possibly lost. Here, it can be observedthat a typical wobble drive, such as drive 190, can have an overallheight of 12-15 inches, which is about twice or more than the overallheight of the drive of the invention.

The more central location of the drive mechanism of the invention, andthe force canceling capability thereof, also provides the advantage ofrequiring less support structure at the sides of the header.

Further, it should be noted that directional references herein,including forward, rearward, sideward, upward and downward, are forreference purposes only, and are not intended to limit the presentinvention to any particular orientation or in any way.

Still further, in FIG. 10 combine 20 is shown including an alternativeheader 198 which is a representative draper type header, including acompact sickle drive mechanism 66 constructed and operable according tothe teachings of the present invention, like parts of header 198 andheader 22 being identified by like numerals. Draper header 198 includesa sickle 30 extending across a forward edge portion 32 of a floor 28,between first and second side edge portions 40 and 42 of the floor.Sickle 30 is composed of a first cutter bar assembly 44 in end to endrelation with a second cutter bar assembly 46. A reel 34 is disposedabove sickle 30. A pair of elongate draper belts 200 and 202 extendedsidewardly along and form a portion of floor 28, and are movable towardthe center of the header for conveying cut crops through a cropconveying area to a center belt 204 operable for conveying the croprearwardly into a mouth or inlet opening of a feeder 26 of combine 20.Compact sickle drive mechanism 66 of header 198 is constructed andoperable in the above-described manner, and provides all of the featuresand advantages of sickle drive mechanism 66 of header 22. Here, it canbe observed that upper cover 84 of compact sickle drive 66 isstreamlined and has a low profile so as to be substantially unobtrusiveto crop flow over floor 28.

In FIGS. 11 and 12, draper header 198 is illustrated including andconfigured for use of two compact sickle drives 66 constructed andoperable according to the teachings of the present invention, like partsof this header 198 and previous headers 22 and 198 being identified bylike numerals. Here, sickle 30 of draper header 198 is comprised of fourcutter bar assemblies 206, 208, 210 and 212 extending in end to endrelation between edge portions 40 and 42 of a floor 28 of the header.Cutter bar assemblies 206 and 208 are connected in reciprocatingsideward driven relation to compact sickle drive 66 on the left side ofthe machine as viewed in the drawing, and cutter bar assemblies 210 and212 are connected in reciprocating sideward driven relation to drive 66on the right side. Drives 66 are constructed and operable as describedabove. Here, it can be observed in reference to FIG. 12 that drives 66are supported beneath draper belts 200 and 202. The location of reel 34above sickle 30 is also illustrated in FIG. 12. Thus, it should beapparent that compact sickle drive mechanisms of the invention can beused with a wide variety of header constructions.

In FIG. 13, a conventional agricultural windrower 214 is illustratedincluding a header 216 including a compact sickle drive mechanism 66constructed and operable according to the teachings of the presentinvention, like parts of header 216 and headers 22 and 198 beingidentified by like numerals. Header 216 includes a sickle 30 extendingalong a forward edge portion of a floor 28, and a reel 34 disposedgenerally above sickle 30. Sickle 30 and reel 34 are constructed andoperable similarly to those items of header 22. In particular, sickle 30includes a first cutter bar assembly 44 and a second cutter bar assembly46, both connected in reciprocating sideward driven relation to drivemechanism 66. Mechanism 66 is incorporated into floor 28 in essentiallythe same manner as described in reference to header 22 above.

It will be understood that changes in the details, materials, steps, andarrangements of parts which have been described and illustrated toexplain the nature of the invention will occur to and may be made bythose skilled in the art upon a reading of this disclosure within theprinciples and scope of the invention. The foregoing descriptionillustrates the preferred embodiment of the invention; however,concepts, as based upon the description, may be employed in otherembodiments without departing from the scope of the invention.Accordingly, the following claims are intended to protect the inventionbroadly as well as in the specific form shown.

1. An epicyclic drive of a sickle comprising: a first input elementsupported on a housing for rotation about a first central rotationalaxis therethrough; a second input element supported on the housing forrotation about a second central rotational axis therethrough a firstpinion gear supported in connection with the first input element forrotation relative thereto about a first eccentric axis offset from andparallel to the first central rotational axis; a second pinion gearsupported in connection with the second input element for rotationrelative thereto about a second eccentric axis offset from and parallelto the second central rotational axis; a first ring gear supported onthe housing concentric with the first input element and enmeshed withthe first pinion gear such that rotation of the first input elementabout the first central rotational axis will cause the first pinion gearto rotate around the first ring gear about the first central rotationalaxis and simultaneously rotate about the first eccentric axis; a secondring gear supported on the housing concentric with the second inputelement and enmeshed with the second pinion gear such that rotation ofthe second input element about the second central rotational axis willcause the second pinion gear to rotate around the second ring gear aboutthe second central rotational axis and simultaneously rotate about thesecond eccentric axis; a first eccentric element fixedly connected tothe first pinion gear so as to be rotated thereby about the first ringgear and the first central rotational axis when the first input elementis rotated; a second eccentric element fixedly connected to the secondpinion gear so as to be rotated thereby about the second ring gear andthe second central rotational axis when the second input element isrotated; a first knife head bearing supported on and extending aroundthe first eccentric element; a second knife head bearing supported onand extending around the second eccentric element; a first knife headassembly connected to a first sickle knife assembly, the first knifehead assembly supported on and extending around the first knife headbearing and configured and restrained for sideward movement only, so asto transfer only sidewardly directed components of rotations of theeccentric element to the sickle knife assembly; a second knife headassembly connected to a second sickle knife assembly, the second knifehead assembly supported on and extending around the second knife headbearing and configured and restrained for sideward movement only, so asto transfer only sidewardly directed components of rotations of thesecond eccentric element to the second sickle knife assembly; and thefirst and second knife head assemblies each including a sidewardlyextending arm portion, wherein the arm portions of the knife headassemblies extend from opposite directions toward the center of thedrive.
 2. The drive of claim 1, wherein the first and second knife headassemblies are each restrained by at least one roller.
 3. The drive ofclaim 2, wherein the at least one roller is mounted for rotation on thehousing.
 4. The drive of claim 2, wherein each arm portion is disposedbetween at least two of the rollers for sideward movement only.
 5. Thedrive of claim 4, wherein the arm portion is configured for transferringforces generated by the sideward movements, to the housing through therollers.
 6. The drive of claim 4, wherein the rollers are disposedforwardly and rearwardly of the arm portion, respectively.
 7. The driveof claim 1, wherein the knife head assemblies are restrained forsideward movement only, by rollers, and will move in opposite sidewarddirections during operation of the drive.
 8. An epicyclic drive of asickle comprising: a first input element supported on a housing forrotation about a first central rotational axis through the first inputelement; a second input element supported on the housing for rotationabout a second central rotational axis through the second input element;a first pinion gear supported in connection with the first input elementfor rotation relative thereto about a first eccentric axis offset fromand parallel to the first central rotational axis; a second pinion gearsupported in connection with the second input element for rotationrelative thereto about a second eccentric axis offset from and parallelto the second central rotational axis; a first fixed ring gear mountedon the housing concentric with the first input element and enmeshed withthe first pinion gear such that rotation of the first input elementabout the first central rotational axis will cause the first pinion gearto rotate around the first ring gear about the first rotational axis andsimultaneously rotate about the first eccentric axis; a second fixedring gear mounted on the housing concentric with the second inputelement and enmeshed with the second pinion gear such that rotation ofthe second input element about the second central rotational axis willcause the second pinion gear to rotate around the second ring gear aboutthe second central rotational axis and simultaneously rotate about thesecond eccentric axis; a first eccentric element fixedly connected tothe first pinion gear so as to be rotated thereby about the first ringgear and the first central rotational axis when the first input elementis rotated; a second eccentric element fixedly connected to the secondpinion gear so as to be rotated thereby about the second ring gear andthe second central rotational axis when the second input element isrotated; a first knife head bearing supported on and extending aroundthe first eccentric element; a second knife head bearing supported onand extending around the second eccentric element; a first knife headassembly connected to a first sickle knife assembly supported formovement in predetermined sideward directions transverse to the firstcentral rotational axis only, the first knife head assembly beingsupported on and extending around the first knife head bearing andconfigured so as to transfer sidewardly directed components of rotationsof the first eccentric element into sideward reciprocating movements ofthe first sickle knife assembly when the first input element is rotated,the first knife head assembly being restrained by at least one elementconnected to the housing so as to be movable only sidewardly and fortransferring forces exerted against the first knife head assembly to thehousing; a second knife head assembly connected to a second sickle knifeassembly supported for movement in predetermined sideward directionstransverse to the second central rotational axis only, the second knifehead assembly being supported on and extending around the second knifehead bearing and configured so as to transfer sidewardly directedcomponents of rotations of the second eccentric element into sidewardreciprocating movements of the second sickle knife assembly when thesecond input element is rotated the second knife head assembly beingrestrained by at least one element connected to the housing so as to bemovable only sidewardly and for transferring forces exerted against thesecond knife head assembly to the housing; and the first and secondknife head assemblies each including a sidewardly extending arm portion,wherein the arm portions of the knife head assemblies are orientedspaced apart so as to extend toward each other in opposite sideward andparallel directions.
 9. The drive of claim 8, wherein the at least oneelement restraining the first and second knife head assemblies comprisesa roller engaged with each respective arm portions extending sidewardlyfrom the knife head assembly.
 10. The drive of claim 9, wherein each armportion has a sideward extent which is at least equal to an extent ofsideward movement of the sickle knife assembly.
 11. The drive of claim8, wherein the sickle knife assembly extends along a front edge portionof a floor of a header for an agricultural harvesting machine, and eachknife head assembly extends forwardly to the sickle knife assembly frombeneath the floor so as to be in offset relation to each sickle knifeassembly.
 12. The drive of claim 8, wherein the input elements arecommonly driven, and the eccentric elements are in timed relation one tothe other such that the sideward reciprocating movements of the knifeassemblies will be at least substantially in opposite sidewarddirections and such that sideward forces exerted by the movements willat least substantially cancel one another.
 13. Sickle apparatus for aheader for an agricultural plant cutting machine, comprising: anelongate first knife assembly supported on the header adjacent to asidewardly extending first forward edge portion of a floor of the headerfor reciprocal sideward movement therealong; an elongate second knifeassembly supported on the header adjacent to a sidewardly extendingsecond forward edge portion of the floor of the header for reciprocatingsideward movement therealong in generally end to end relation to thefirst knife assembly; and a compact sickle drive mechanism disposedwithin a housing supported on the header adjacent to or under, thefloor, spaced from opposite sides of the header, and rearwardly of thefirst and second knife assemblies, the sickle drive mechanism includinga first epicyclic drive operable for reciprocatingly moving the firstknife assembly sidewardly relative to the first forward edge portion ofthe floor, and a second epicyclic drive operable for reciprocatinglymoving the second knife assembly sidewardly relative to the secondforward edge portion of the floor, each of the epicyclic drivesincluding an eccentric element supported for eccentric rotation about anat least generally vertical central rotational axis of the epicyclicdrive, a knife head bearing supported on and extending around theeccentric element, and a knife head assembly connected in drivingrelation to a sickle knife assembly to be reciprocatingly moved by theepicyclic drive, each knife head assembly extending around the eachrespective knife head bearing and each knife head assembly including asidewardly extending arm portion engaged with at least one element onthe housing and configured for transferring forces generated during thereciprocating movements to the housing wherein the arm portions of theknife head assemblies are oriented spaced apart so as to extend fromopposite sideward and parallel directions, further wherein the armportions extend toward the center of the sickle drive mechanism. 14.Sickle apparatus of claim 13, wherein the knife head assemblies areconfigured and oriented such that the forces transferred to the housingby the epicyclic drives will at least partially cancel one another. 15.Sickle apparatus of claim 13, wherein the at least one element on thehousing comprises rollers which allow only sideward movement of the armportion relative thereto.